Paint is a good thing, but you can have too much of it. And the paint store will not take back extra gallons of that lovely orchid tint you selected. For a rough estimate of how much paint you'll need, measure the room's perimeter (in feet) and multiply that number by the wall height in feet. From this result, subtract 20 square feet for each door and 14 square feet for each window. Divide that number by the spreading rate listed on the paint can. That's the number of gallons you'll need.

There's an Einsteinian formula for calculating how much trim paint you'll need, but most painters just figure it will be one-fourth what is needed for the walls. The main thing to remember: If it's more than two quarts, get a gallon; it's always cheaper.

continue reading below

Move Everything to the Middle

It's amazing how many people try to paint with a room full of furniture in their way. Try this method instead:

Remove everything you can; cluster everything else in the center of the room and cover it with plastic or canvas drop cloths.

Use more canvas to cover the floor; spatters and spills collect on plastic and smear underfoot, and plastic is slippery, too.

Take everything off the walls, including covers for electric receptacles and light switches. (While you're at it, write the color and amount of paint you are using for that room on a piece of masking tape and stick it to the inside of the switch for later reference.)

Cover stationary light fixtures with plastic trash bags (as long as the lights won't be on while you paint).

Loosen all door locks, and remove door hardware.

Gently pull all nails and picture hooks. Fill the holes with premixed surfacing compound using a 3-inch putty knife, or fill with quality paintable caulk.

Tape Tips

Use masking or painter's tape to protect every place you don't want paint, such as doorknobs, any hardware you couldn't remove, and windows.

There are two schools of thought about painting window muntins -- those decorative moldings that separate panes of glass on some windows. Some people tape the glass next to window muntins to minimize the time spent scraping paint off the glass, but others say it's faster to let a little paint touch the panes and scrape it off later with a razor blade. It's your call.

If your home was built after 1940, chances are the walls and ceilings are made of wallboard, also called plasterboard or drywall. These are rigid, factory-made sandwich panels (usually 4 feet wide) nailed to interior studs. Seams, nails, and dents from hammering the panels in place all conspire to confound a painter.

Repairing existing drywall is usually not difficult. The most common problems are popped nailheads (nails that come loose and appear as bumps) and peeling joint tape. Gently tap the nails back into place, and cover the dents with a thin layer of a plasterlike mixture called joint compound, which you sand and repaint. To fix peeling tape, cut away the loose piece with a sharp knife and wipe off any flakes of old adhesive. Cover the open seam with fiberglass mesh tape cut exactly to fit. Cover the tape with a smooth layer of joint compound (use a 5-inch flexible joint knife for this), and sand lightly after it dries. Repeat, using larger knives (an 8-inch and then 10-inch knife) so the repair's edges blend with the surrounding surface. Finally, smooth with a damp sponge and repaint.

Fixing a drywall hole (usually caused by a doorknob, sometimes by deranged sports fans) is trickier. Draw a rectangle around the damage, drill 1/2-inch starter holes at each corner, and cut away the rectangle with a keyhole saw. Place two 1x4 strips of wood just behind the wall surface so they frame the hole, leaving at least an inch of wood showing around the hole's sides. Use drywall screws to attach the strips at each corner, screwing through the surrounding drywall just outside the hole edges.

To fill the neat rectangular hole, cut a drywall insert about 1/8 inch smaller than the hole, fit it in place, and secure it to the side-mounted wood strips with drywall screws (countersink them just below the wall surface). Cover the seams and screw holes with self-adhering fiberglass mesh, and cover that with joint compound using a 4-inch joint knife. Using progressively wider joint knives, apply three to four coats of compound, smoothing and feathering the edges. Prime before painting.

If your room contains new drywall, it should be smooth before you prime and paint it. Check that seams and nails have been covered with joint tape and compound, and that there are no rough spots. If the wall is smooth, there will be no telltale show-through after painting.

To fill small nail holes or narrow cracks in plaster, surfacing compound works fine. Tip: Undercut the edges of the crack and dampen them with water to help the compound adhere. Patching larger holes in plaster walls, however, requires different materials and techniques. Use a screwdriver to clean out the hole or crack, removing all loose plaster--including pieces in between and behind the lath strips. Nail a piece of hardware screen to the lath to provide a grip surface for the plaster. Apply patching plaster (not the same as drywall compound) in three shallow coats, following manufacturer's instructions. Apply drywall compound for the final coat, using a wide knife to spread and feather the edges. Sand smooth; prime and paint.

Lots of Layers?

If your woodwork has been painted so many times the detail is hidden, you may need to remove the old layers of paint with either a chemical stripper or a heat gun. Today's chemical strippers are much less toxic than earlier types. Some are water-soluble or low-odor, although these tend to work more slowly and may need several attempts. Apply stripper with an old paintbrush. When bubbles form, use a scraper and steel wool to remove the softening paint.

If you opt for a heat gun, hold it about 1 foot from the surface, and scrape as the paint bubbles up. The trick is to keep the paint hot, without burning the wood. Wear a heavy leather glove on your scraping hand, and keep a fire extinguisher close by.

Newer Woodwork

For newer woodwork that needs a fresh coat of paint, you might simply dull the surface with a deglosser, sold at paint and hardware stores. Deglossers break down a shiny finish and create a surface new paint can stick to. Light sanding with 120-grit sandpaper will also create a good, bondable surface for new paint.

Some words of caution: When using strippers and deglossers, provide cross ventilation and wear protective clothing and an approved respirator, not just a disposable dust mask. Ban smoking in the work area, and wash your hands before you eat, drink, or smoke in case you picked up any chemical residue.

Remodeling dust and dirt, as well as everyday grease and grime, needs to come off your walls before you swipe a single brushstroke of paint. Anything that comes between the paint and the surface -- even minute particles of dust -- affects the paint's adherence and finish.

For ordinary soiled walls, you can use a mild commercial cleaner and water, but an abrasive cleaner will help roughen the surface a bit to improve bonding. Trisodium phosphate (washing soda -- not baking soda) also makes a good prepaint cleaner, especially for areas that may have a greasy film. (Note: Some states ban the use of phosphate-base cleaners.)

Using a sponge mop, wash the ceiling first, squeezing the mop frequently to reduce drips. Wash the walls one section at a time, working from bottom to top. If you start at the top, wash water can drip onto the dry, dirty walls and cause it to stain. Rough-texture walls are difficult to wash with a sponge. Use white rags instead. Remember to shut off the electricity at the circuit breaker box to rooms where you'll be sloshing water around.

If your rooms were painted before 1978, the paint may contain lead. This substance is extremely toxic, especially to children, and can damage the nervous system. Because it enters the body through dust, fumes, or, in the case of children, chips of paint that are eaten, lead is a common remodeling hazard.

If you suspect lead is present in your painted walls, check stores for consumer lead testing kits. The Environmental Protection Agency can also advise you about how to deal with lead during a remodeling. It's important to take precautions before doing any remodeling work such as stripping paint or tearing down walls. For more information, visit the National Lead Information Center Web site at www.epa.gov/lead/nlic.htm or call the NLIC at 800-424-5323.